Colloidal aluminum hydroxide



Patented 3y i 133 arouses g COLLOEAL AL Harold W. Jones, Columbus, @hio, assignor to The (lolumbus lPhai-macal Company, fiolbus, Ohio, a corporation or Ghio Application March 2, 193%,

serial No. cases 6 our (on. rea -rs) ill with a small amount of a protective organic colloid such as acacia or gelatin.

The substance commonly known as aluminum hydroxide and generally given the formula AMOHM, is ordinarily prepared by precipitation is from a solution of a soluble salt of aluminum by the addition of ammonium hydroxide or a solu tion of sodium carbonate, or of other alkali carhonate. Zihe freshly precipitated or gel form is highly adsorptive, and its therapeutic value as an go antacid depends, not so much on its power to neutralize acidity by chemical means, as it is dinicultly soluble in dilute acid, but upon its power to adsorb excess hydrochloric acid when introduced into the stomach, and also upon the fact that it is capable of forming a non-toxic protective coating over the stomach mucosa.

The gel thus formed is in an inorganic colloidal state to which it owes the above valuable properties. However, in the preparation of dried corm- .mercial aluminum hydroxide, the colloidal condition which existed when it was freshly prepared and still in a moist state is completely destroyed in the dehydrating process, and the ordinary dried product will not again return to the hydrated or 35 colloidal state when mixed with water.

The purpose. of this invention is to produce a partially dehydrated aluminum hydroxide, "in powder form, which will return to the hydrated form when mixed with water, the result being 6% accomplished by the addition of'aprotective colloid such as acacia, dextrin, tragacanth, gelatin, pectin, the starches, muciiage such as that made from quince seed, elm bark or Irish moss, or other soluble organic colloid to the solution of the alum salt before the precipitation talres place. en formed in this manner the colloidal particles of we: hydromde are believed to be encased by a protective coating of the organic colloid. After r :1' if the powder is again mixed with water, the protectivecoating redisselves and the colloidalm or alumin hydromde is recovered in a state similar to that in which it wi when freshly precipitated, the presence of a small percentage of hydrochloric acid such as in fotmd in the stomach, assisting result.

sin:- of ammonium alum, is dissolved in 1000 cc. previously dissolved 0.8'75gram of acacia; ammonia water is added to this solution until precipitation is complete. The

' precipitate is washed free from soluble salts with.

water, dried at a temperature of about 40 0. and when dry reduced to a fine powder. If this powder is shaken'with water, containing about 0.3% of hydrochloric acid, it will return to its original gelatinous state, forming a gel, and 1 gram 'of the powder is capable of adsorbing 3 to 5 cc. of N/ hydrochloric acid, whereas the compound 10 produced in the usual way, without the use of a protective colloid, will not again become hydrated and is devoid placid adsorption power.

. reverting to a gelatinous state similar tothat of freshly precipitated aluminum hydroxide, and

possessing .iriarlred acid-adsorbing power;

2. The invention defined in claim 1, wherein said water-soluble organic colloid is a gum.

3. The invention defined in claim 1, wherein said water-soluble organic colloid is starch.

d. The invention defined in claim 1. wherein said water-soluble organic colloid is gelatin.

5. The process oi making a partially dehydrated aluminum hydroxide, capable, upon being mixed with water, of assuming a gelatinous'state similar to that or ireshly precipitated aluminum hydroxide, which comprises precipitating aluminum hydroxide, hy means of a suitable basic precipitant, from a water solution of an aluminum salt also containing a relatively small amount of a soluble organic protective colloid, separating the $0 resultant gelatinous precipitate anddrying it at a. temperature sciently high to effect partial dehydration, and pulverizing the dried precipitate.

6. The procem of l'fl'iil drated aluminum hydroxide capable, upon being mixed with water, of assng a gelatinous state similar to that'oi fry precipitated aluminum hydroxide, which comprises precipitating aluml-.

. num hydroxide, by means of a suitable basic prefrom soluble salts, g 'it ata temperature appro ately 46 (2., and precipitate.

- the dried w. mes;-

a partially dehy- 

